The process of making a flocculating agent for purifying and clarifying water for various applications, including human consumption is the field of the present invention.
The present processes of purifying and clarifying water use inorganic salts, mainly aluminum and iron salts, as coagulating and flocculating agents. The inorganic salts through its coagulating and flocculating properties remove the impurities from the water.
The present invention embodies a manufacturing process of a quaternary tannate as a coagulating/flocculating agent. The flocculating agent is used for treating drinking water and water used in industry, such as for boilers and cooling towers. The present invention embodies the treatment of industrial effluents and domestic sewage with a synthetic coagulating/flocculating agent with organic and vegetable properties.
The coagulating/flocculating agent is a vegetable polyelectrolytic cation. The raw material for the manufacturing of polyelectrolytic cation is pyrochatechin tannin, which is an extract of Acacia mearnsii bark. This tannin has cationic properties. We obtained the vegetable polyelectrolytic cation by reacting the vegetable tannin, a phenolic polymer that acts as a nucleopbile in the face of an electrophilic system, with reaction products of an aldehyde reacting with amines.
An embodiment of the present invention is a process for preparing the coagulating/flocculating agent. This process is comprised of the following steps:
a) mixing an aldehyde, an ammonium salt, and a mineral acid catalyst in a reaction vat at a temperature below 45xc2x0 C. at environmental pressure in an aqueous medium;
b) reacting said mixture by heating said mixture in a temperature range from about 60xc2x0 C. to 75xc2x0 C. until a colorless liquid is obtained, usually takes from 5 to 9 hours;
c) reacting said obtained colorless liquid with an aqueous tannin solution by stirring at normal pressure at a temperature range of from about 45xc2x0 C. to about 97xc2x0 C. for at least 5 hours to obtain a viscous liquid, wherein the viscous liquid has a viscosity of about 30 seconds in a No. 4 Ford cup; and
d) optionally, atomizing said viscous liquid at temperatures from about 170xc2x0 C. to about 240xc2x0 C. to obtain a uniformly grained powder.
The process of preparing process the coagulating/flocculating agent is based on a Mannich reaction. Initially, an ammonium salt reacts with an aldehyde using a mineral acid catalyst to give a complex mixture of primary and secondary amines. The complex mixture then reacts with the tannin using acid catalysis, which results in the vegetable polyelectrolytic cation, the coagulating/flocculating agent of the present invention.
The preparation of the quaternary ammonium tannate use the following materials:
(i) A vegetable tannin, that is chemically a phenolic polymer. The monomeric structure of this phenolic polymer is flavin-3-ol. The amount of vegetable tannin used is from about 44% to 56% by weight of the total mixture.
(ii) An aldehyde, that is preferably an aliphatic aldehyde or furfuraldehyde. The more preferable aliphatic aldehydes are formaldehyde and paraformaldehyde. The most preferable aliphatic aldehyde is a formalin solution, which is a solution of formaldehyde. The amount of aldehyde used is from about 28% to 38% by weight of the total mixture.
(iii) A mineral acid catalyst, that is capable of catalyzing a Mannich reaction. The more preferable mineral acid catalyst is a chloridic acid. The most preferable mineral acid catalyst is hydrochloric acid. The amount of mineral acid catalyst used is from about 5% to 18% by weight of the total mixture.
(iv) A salt, that is capable of reacting in a Mannich reaction, such as ammonium salt. The more preferable salts are salts of methylamine, ethylamine, monoethanolamine, diethanolamine or ammonia. The most preferable ammonium salt is ammonium chloride. The amount of ammonium salt used is from about 17% to 32% by weight of the total mixture.
The resulting product has the general chemical structure of (I) shown below. 
The coagulating/flocculating agent of the present invention is distinct from the traditional agents by its capacity to create chelates with metals dissolved in water. These chelates immobilize the metals next to the coagulating/flocculating agent, and cause them to settle. The immobilized metal is subsequently removed with the generated sludge. This feature is especially efficient when removing ferrous ions present in the water.
Another important feature of the present invention is that the coagulating/flocculating agent acts in a broad pH range, which is contrary to the inorganic salts presently used. The inorganic salts in the present field act in a narrow range of pH. The fundamental difference of the present invention is that the cationic coagulating agent of vegetable origin does not need to be hydrolyzed with the environment to neutralize the charges of the colloidal matter in the water; thus, the cationic coagulating agent of vegetable origin does not alter the pH of the water. This has the added advantage of not requiring an alkalizing agent in the treatment of the water.